Conventionally, in an image forming apparatus such as a digital multi-function peripheral called as a MFP (multi-function peripheral), a scanner section and a printer section are arranged. A document is read and the read image data is processed by the scanner section, and then the processed image data is printed by the printer section.
Further, in recent years, there is a MFP which is provided with not only a copy function, a print function and a scanner function, but also a FAX (facsimile) function using the public line. In addition, there is also a MFP linked with an external personal computer and the like by connecting the MFP with a network.
In such a MFP, various measures have been taken to reduce power consumption. In the past, for example, if an authentication is carried out to authenticate a user through an IC card, the image forming apparatus is restored from the power saving mode to the general mode.
Further, there is also an example in which authority for using the MFP is given to a specific user. If it is authenticated by the MFP that a user is the user who has the authority, the electric power is fed to each block of the MFP, in this way, it is possible to use the MFP.
However, in the past, though the user who has the authority can use the MFP, the electric power is also fed to the unused blocks. Thus, there is a disadvantage that extra power is consumed.